Exploring beneficial uses of ferrochrome slag: a case study of a South African Ferrochrome industry
South Africa is the leading player in the international ferro-alloy industry due to its abundance of natural resources. Ferrochrome (FeCr) slag is a waste material obtained from the manufacturing of ferrochromium alloy. Typically, it contains 30% silicon dioxide (SiO2), 26% aluminium oxide (Al2O3) and 23% magnesium oxide (MgO) in different phases such as spinel and fosterite, with minor traces of ferrous/ferric oxides, chrome oxides and 2% calcium oxide (CaO). Because of its constituents, the FeCr slag has value and can be used for beneficial purposes, however, if not managed correctly, it may have adverse impacts on health and the environment. The South African National Waste Management Strategy advocates that waste is preferably re-used, recycled and recovered, and disposed to land as a last resort. However, the re-use, recycling and recovery of waste have, to date, not been implemented by industry as a preferred option to disposal. This is partly due to obstacles presented by waste management licencing requirements, financial implications and potential adverse impacts. Recently, the Waste Exclusion Regulations, have been promulgated, to promote the beneficial use of waste. This study aimed to explore the beneficial uses of FeCr slag produced by a selected South African ferroalloy industry. In support thereof, the objectives of this study included: determining the properties of FeCr slag, the risks related to the beneficial use of FeCr slag, exploring the potential beneficial use of the FeCr slag and lastly determining the challenges of and opportunities for the beneficial use of FeCr slag. The results of the waste classification process, leachability test, and risk assessment performed in terms of the Waste Exclusion Regulations indicated that the FeCr slag is non-hazardous and presents a negligible risk to the environment and health of people. There are several options within the South African context for the beneficial use of FeCr slag, which include the use of FeCr as aggregate, road construction material, construction material. The results of this study supports that reuse of FeCr slag has financial, environmental and business/operational benefits that will ensure sustainability of natural resources and circular economy.